Inductive heating of tissues using alternating magnetic fields and uses thereof

ABSTRACT

Provided herein are methods and devices for inductively heating a tissue to effect a biological response in the tissue or in a biomolecule comprising the same. The methods and devices comprise means for applying a high frequency alternating magnetic field via an inductive coil comprising an applicator to the tissue and means for monitoring feedback from the alternating magnetic field to control and/or adjust heat, for example, in the tissue, which further includes a means for cooling the tissue. Particularly, the device may be a hand held piece that incorporates or has at least an applicator, including a radiofrequency energy generator and output, an inductive coil, an impedance matching system, a cooling system, including a thermally conductive surface and a coolant housing containing a coolant that circulates through the thermally conductive surface, and a feedback monitor. Optionally, the device may comprise a tissue-shaper.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part under 35 U.S.C. § 120 ofpending U.S. Ser. No. 12/080,897, filed Apr. 7, 2008, now U.S. Pat. No.10,271,900, which claims benefit of priority under 35 U.S.C. § 119(e) ofprovisional application U.S. Ser. No. 60/922,249, filed Apr. 6, 2007,the entirety of both of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to the fields of biomedicalengineering, biochemistry, medical treatment, and surgical procedures.More specifically, the present invention provides methods, devices, andcompositions for inducing changes in tissues, biomolecules, includingbioactive molecules. These changes are notably useful for inducingalterations in tissues, most notably in skin, for cosmetic purposes.

Description of the Related Art

Heating of tissue is a fundamental physical event in many differentmedical procedures. Depending on the time-temperature history of thetissue, a cascade of physical, chemical, and biological events occurswhen tissue is heated. These events can lead to a beneficial ordeleterious response. One example of a beneficial response is thereduction or elimination of the appearance of skin wrinkles as a resultof heat induced tissue contraction and skin thickening as a result ofneocollagen formation following heat stimulation in tissues.

Skin wrinkles are often the consequence of advancing age and sunexposure. With increasing age and excessive sun exposure, skin qualitydeteriorates. This is due, in part, to changes in hydration andepidermal thickness, and on a molecular scale, to a decrease in theamount of collagen in the dermis. Further, subcutaneous fat accumulatesor atrophies leading to furrowing of the skin, which produces wrinkles.In today's society, the appearance of skin wrinkles is often viewednegatively and so there is a desire in the community for a means tosafely reduce or eliminate wrinkles.

For many years, wrinkles have been treated with chemical peels ormechanical dermabrasion, cosmetic medical procedures in which thesurface of the epidermis of the skin, i.e., the stratum corneum, isremoved chemically or by abrasion, such as sanding, respectively. In thelate 1980s, laser ablation procedures for skin resurfacing weredeveloped and approved.

Some of the first laser ablation procedures involved CO₂ lasers, whichablated some or all of the outermost layer of the epidermis, the stratumcorneum. The CO₂ lasers could often generate enough heat in the dermisto cause a tissue contraction. This and subsequent repair of theepidermis and stratum corneum led to visible effects including wrinklereduction and smoothing of the skin.

Nonetheless, inadvertent and lasting damage from burns to the epidermiswas often evident, hypo- or hyper-pigmentation was fairly common, andpatients receiving these treatments were required to stay indoors forweeks in order to avoid damaging ultraviolet rays from sunlight in theirnow unprotected dermal layers of skin. These lasers gave way to variouslasers that operated at different wavelengths with the goal of reducingthe negative effects. Today, laser procedures that are non-ablative andless damaging to surrounding tissues have replaced most of theseoriginal laser procedures. These lasers are much safer and produce muchless damage to surrounding tissues, however much of the beneficialeffects have also been lost, particularly with regard to skintightening.

In the mid to late 1990s, another cosmetic technique for skin wasdeveloped that involves a non-ablative thermal alteration to skin. Thisprocedure was based on concepts drawn from radiofrequencyelectrosurgical devices where electrical current is introduced into thepatient via an electrode in electrical contact with tissue and exitsthrough a ground electrode in contact elsewhere on the patient. Thesedevices are referred as capacitive coupled devices whereby current flowsbetween electrodes, and on the way, fields build up where tissues ofrelatively greater resistance are encountered.

In the case of skin, the stratum corneum and epidermis are only weaklyconductive, so fields and heat build up there. Current flows through theconductive dermis, and again encounters resistance at the adiposallevel, again resulting in heat generation. In skin, the treatmenttechnique is referred to as radiofrequency (RF) skin rejuvenation (1).

In the skin, beneficial radiofrequency rejuvenation can result in tissuecontraction as heat flows from the areas of field concentration, such asthe adipose layer and epidermis, and into the dermis. Furthermore, abeneficial wound response to the heat in the dermis can lead toproduction of new collagen, and ultimately the skin may thicken. Whentreating the skin with RF devices, it is necessary to provide aconductive coupling gel between the skin and electrodes to allow forcurrent flow.

Capacitive-coupled devices may result in negative, and sometimes severeconsequences with regard to damage to tissues where the electric fieldsconcentrate. Current generally follows the path of least resistance andthus it is not always predictable or controllable where its effects willoccur. Any current that flows through the body is potentially hazardous.As the electric fields concentrate at non-conductive interfaces,electrical burns and heat damage may become evident at these interfaces.Burns are common at the electrodes in electrosurgical devices, andsimilarly, RF rejuvenation devices may also produce burns. In skin,capacitively-coupled radiofrequency heating exhibits preferential powerabsorption in the epidermis and in lower-conductivity subcutaneous fat.In other words, capacitive-coupled devices preferentially heat tissueswith higher specific resistance (2-3). As a result, these tissues are atrisk for damage.

To counter the effects of deleterious heating at the skin surface,capacitive-coupled skin rejuvenation devices (4), and lasers (5-6),often use some mechanism to cool the surface of the skin, therebyavoiding most of the damage to the outer epidermis and stratum corneum.Nonetheless, the risk of heating adipose tissue below the dermis iseverpresent with RF devices and, anecdotally, patients have complainedof long-term subcutaneous fat atrophy following treatment with thesedevices, with some of these requiring grafting. Efforts to reduce suchdetrimental effects require reduction of power output and have likelyreduced efficacy of these devices.

More recently, additional devices for skin rejuvenation have beendeveloped that employ ultrasound In an attempt to provide specific andlocalized treatment to the dermis. The devices focus the ultrasoundwithin the dermis, or just below to achieve specific heating. Thoughspecificity is improved, cavitation can result in pain and tissuedamage. Burning and necrosis of the epidermis and stratum corneum duringlaser and RF cosmetic skin treatments is of major concern. Thus, variousmethods of skin cooling are often employed, including the spraying ofcryogen on the skin surface or on an applicator, or applying cold air,water or ice to the skin.

In contrast to the aforementioned tissue heating devices and technology,magnetic induction applicators, such as those used in magnetic inductiondiathermy devices primarily induce (eddy) currents to flow alongpathways governed by electric conductivities, hence depositing morepower in tissues of higher conductivity (2). Inductively coupleddiathermy units use induced eddy currents to heat tissue, especiallytissue, such as muscle, with high water content (7), but only weaklyaffect tissues with high fat content (8). Nonetheless, diathermy devicesare used for deep heating of tissue structures, and their effects onthin tissue layers such as the dermis have yet to be described.

Thus, there is a recognized, continuing need for improved methods anddevices for specific heating of the thin dermal layer of skin with ahigh degree of specificity, efficacy and safety. Moreover, there is arecognized need for improvements in the use of magnetic inductionmethods and devices to heat tissue near or at the skin surface, andparticularly, for specific dermal heating to achieve a cosmetic result.

The prior art is deficient in methods and devices for highly efficientand safe non-invasive heating of the skin, with high specificity for thedermis, while protecting collateral tissue structures. The presentinvention fulfills this longstanding need and desire in the art.

SUMMARY OF THE INVENTION

The present invention is directed to a method for inducing heat in thedermis of a subject to effect a biological response. The methodcomprises the step of applying a high frequency alternating magneticfield to the skin of the individual such that the magnetic fieldinductively heats the dermis, thereby effecting the biological responsetherein. In a related method an area of skin is mechanically orpneumatically shaped prior to applying the high frequency alternatingmagnetic field thereto. In another related method, one of radiantenergy, acoustic energy or vibrational energy is applied to the skinconcurrently or sequentially with the high frequency alternatingmagnetic field. In yet another related method, feedback from themagnetic field is monitored and an amount of heat induced in the dermisin the individual is adjusted based on the feedback. In yet anotherrelated method, the dermis of the subject is cooled to disperse heatgenerated therein.

The present invention also is directed to a device for heating a tissuein a subject. The device comprises a means for generating a highfrequency alternating magnetic field to alter one or both of a tissue ora biomolecule comprising the same in the subject and a means forcontrolling the alteration of the tissue or biomolecule. A relateddevice further incorporates a means for housing the device. Anotherrelated device further incorporates a means for monitoring feedback fromone or more of another source of radiant energy, plasma energy, acousticenergy, or bipolar or monopolar electrosurgical energy.

The present invention is directed further to another device for heatingtissue in a subject. The device comprises a hand held piece thatincorporates or has an applicator with a radiofrequency energy generatorand an energy output, an impedance matching network in electricalcontact with the applicator, an inductive coil connected to the energyoutput, an end plate at a distal end of the hand held piece that has athermally conductive surface positionable on the tissue and, optionally,is in thermal contact with the inductive coil. A related device furthercomprises a coolant housing containing a coolant and in fluid contactwith the inductive coil and, optionally, the thermally conductivesurface. Another related device further comprises a mechanicaltissue-shaper or a pneumatic tissue-shaper in contact with the tissue.Another related device further comprises a heat feedback monitorpositioned distal to the induction coil or proximate to the tissue.

Other and further aspects, features, and advantages of the presentinvention will be apparent from the following description of thepresently preferred embodiments of the invention given for the purposeof disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the matter in which the above-recited features, advantages andobjects of the invention, as well as others that will become clear, areattained and can be understood in detail, more particular descriptionsof the invention briefly summarized above may be had by reference tocertain embodiments thereof that are illustrated in the appendeddrawings. These drawings form a part of the specification. It is to benoted, however, that the appended drawings illustrate preferredembodiments of the invention and therefore are not to be consideredlimiting in their scope.

FIG. 1 depicts an applicator that transduces radiofrequency electricalenergy into a magnetic field.

FIGS. 2A-2B depict a front view (FIG. 2A) and a side view (FIG. 2B) of ahand piece incorporating a magnetic field applicator with optionalcooling system.

FIG. 3 depicts the endplate of the hand piece.

FIG. 4 depicts a hand piece incorporating a solenoid-type inductor andpositioning of tissue using pneumatic pressure.

FIG. 5 depicts a circuit diagram of the applicator.

FIG. 6 shows measurements taken at 27 MHz and 600 W. Bovine muscle,bovine fat, ovine skin, and human blood were used for comparison. Thetissues were cut to 2×2×5 cm samples. Each sample was placed directly onthe cap of the 27 MHz device and imaged from above with a Raytek IRthermometer. The device was activated and the time to heat was recorded.(n=3 for each tissue type).

FIG. 7 shows porcine fat, muscle and skin were used for comparison. Thetissue samples were measured for thickness to ensure consistency betweensamples. The samples were between 1.5-2.0 mm in thickness. The sampleswere placed on the faceplate which is 4 mm thick PVC and imaged fromabove with a Raytek IR thermometer. The device was turned on and thetime for the sample to reach 70° C. was recorded. The IR thermometer islimited to recording the tissue surface opposite that which is incontact with the device. Therefore, it is believe that the actualtemperature of the tissue was greater than indicated on the graph.

FIGS. 8A-8C show biopsied samples at the two-week post-treatment timepoint (FIGS. 8B-8C) demonstrating a thickening of the dermis as comparedto untreated controls (FIG. 8A).

FIGS. 9A-9B show biopsied samples before and after treatmentdemonstrating a production of neo-collagen in treated tissues (FIG. 9B)as compared to the untreated controls (FIG. 9A).

FIG. 10 shows a model of the expected mode of action produced byinductive heating on collagen within the treated tissues.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term, “a” or “an” may mean one or more. As usedherein in the claim(s), when used in conjunction with the word“comprising”, the words “a” or “an” may mean one or more than one. Asused herein “another” or “other” may mean at least a second or more ofthe same or different claim element or components thereof.

As used herein, the term “or” in the claims refers to “and/or” unlessexplicitly indicated to refer to alternatives only or the alternativesare mutually exclusive, although the disclosure supports a definitionthat refers to only alternatives and “and/or”.

As used herein, the term “subject” refers to any recipient of at leasthigh frequency alternating magnetic field as a means for inductivelyheating a tissue, for example, the skin or dermis, thereof to cause orto effect a biological response in the tissue or its components orbiomolecules comprising the same.

In one embodiment of the present invention there is provided a methodfor inducing heat in the dermis of a subject to effect a biologicalresponse, comprising the step of applying a high frequency alternatingmagnetic field to the skin of the individual, whereby the magnetic fieldinductively heats the dermis, thereby effecting the biological responsetherein.

Further to this embodiment the method may comprise mechanically orpneumatically shaping an area of skin prior to applying the highfrequency alternating magnetic field thereto. In another furtherembodiment the method may comprise applying radiant energy, acousticenergy or vibrational energy to the skin concurrently or sequentiallywith the high frequency alternating magnetic field.

In another further embodiment the method may comprise monitoringfeedback from the magnetic field and adjusting an amount of the heatinduced in the dermis in the individual based on the feedback. In thisfurther embodiment the step of feedback monitoring may comprise one ormore of detecting heat in the dermis, detecting eddy currents formed inthe dermis, detecting hydration changes in the dermis, or detectingimpedance changes in the dermis. In representative examples detectingheat in the dermis may comprise monitoring heat sensitive liquid crystalmedia or monitoring infrared radiation. Further to this embodimentfeedback monitoring further may comprise monitoring heat generated byone or more of another source of radiant energy, plasma energy, acousticenergy, or bipolar or monopolar electrosurgical energy.

In yet another further embodiment the method may comprise cooling thedermis of the subject to disperse heat generated therein. In thisfurther embodiment the step of cooling the dermis may comprisepositioning a thermally conductive surface in contact with one or bothof the skin or an exterior surface of an inductive coil generating thealternating magnetic field. A thermally conductive surface may be a heatsink that passively disperses heat, may have a coolant circulatingtherethrough, may be a cryogenic material or may have a cryogenicmaterial disposed thereon.

In all embodiments the biological response may be one or more of tissuecoagulation, cauterization, tissue contraction, tissue shrinkage,induction of wound response, production of collagen. Also, the inductiveheating may activate collagen repair and tissue growth or improves skincosmesis by smoothing the skin or reducing skin laxity.

In another embodiment of the present invention there is provided adevice heating a tissue in a subject, comprising means for generating ahigh frequency alternating magnetic field to alter one or both of atissue or a biomolecule comprising the same in the subject; and meansfor controlling the alteration of the tissue or biomolecule.

In this embodiment the means for providing the high frequencyalternating magnetic field may be an applicator having an induction coiland an output for radiofrequency energy. Also in this embodiment themeans for controlling the alteration of the tissue or biomolecule maycomprise a monitoring system for feedback from the high frequencyalternating magnetic field distal to the induction coil or proximate tothe tissue.

Further to these embodiments the device may comprise means for housingthe device. In this further embodiment the means for housing the devicemay be a hand held piece having an impedance matching network and acoupler to couple to an output of a radiofrequency energy source. Also,in this further embodiment the hand held piece further may comprise anend plate at a distal end thereof and having a thermally conductivesurface positionable to contact one or both of the tissue or theexterior of the applicator. Examples of a thermally conductive surfaceare a passive heat sink, a cryogenic material or the thermallyconductive surface has a cryogenic material applied thereto. Inaddition, the hand held piece further may comprise a coolant housingattached thereto and containing coolant which is in fluid contact withone or both of the thermally conductive surface on the end plate and aninductive coil comprising an applicator where the coolant circulatestherethrough. Furthermore, the hand held piece further may comprise amechanical tissue-shaper or a pneumatic tissue-shaper in contact withthe tissue.

In another further embodiment the device may comprise means formonitoring feedback from one or more of another source of radiantenergy, plasma energy, acoustic energy, or bipolar or monopolarelectrosurgical energy. In all embodiments the tissue may be skin.

In yet another embodiment of the present invention there is provided adevice for heating a tissue in a subject, comprising a hand held pieceincorporating an applicator with a radiofrequency energy generator andan energy output; an impedance matching network in electrical contactwith the applicator; an inductive coil connected to the energy output;and an end plate at a distal end of the hand held piece that has athermally conductive surface positionable on the tissue and, optionally,is in thermal contact with the inductive coil.

In a further embodiment the device may comprise a coolant housingcontaining a coolant and in fluid contact with the inductive coil and,optionally, the thermally conductive surface In another furtherembodiment the device may comprise a mechanical tissue-shaper or apneumatic tissue-shaper in contact with the tissue. In yet anotherfurther embodiment the device may comprise a heat feedback monitorpositioned distal to the induction coil or proximate to the tissue. Inall embodiments the tissue may be as described supra.

The present invention provides methods and devices for treatment oftissues in a subject, preferably for cosmetic treatment of skin, with ahigh degree of specificity for the dermis. The devices are magneticinduction devices of such geometry that they provide a concentrated andintense alternating magnetic field to shallow layers of skin, whenplaced in close proximity to the skin. The method involves creating ahigh-frequency alternating magnetic field that, when directed inproximity with tissue, results in the production of heat throughinductive coupling with the tissue thus resulting in the desiredbiologic effect. Representative examples of such biologic effectsinclude, but are not limited to coagulation, cauterization, tissuecontraction or shrinkage, and induction of a wound response that leadsto biomolecular changes. Generally, application of the high frequencyalternating magnetic field itself may induce, or the concomitantproduction of heat may induce, the movement of a charged species orother biomolecule or bioactive molecule or species within the tissueleading to various biological responses, such as, but not limited to,the production of collagen by cells and dermal thickening.

Particularly, utilizing the present methods and devices improves thecosmetic appearance of the skin by controllably heating a superficiallayer of skin, preferably, the dermis. An acute tissue contraction orshrinkage and/or a wound response is effected which leads to theproduction of biomolecules resulting in improved cosmesis. Preferably,the devices are used for the direct heating of moist conductive tissues,such as the viable dermis, during cosmetic skin treatment, and lessefficiently for tissues of low conductivity which may in part be due tolow hydration (e.g. stratum corneum) or of low polarity (adipose),thereby providing a safer means for treating skin. The device and itsmethod of use minimizes the risk of significant burns to the skinsurface, and eliminates charring and the generation of smoke, as it doesnot rely on capacitive coupling for its effects. The patient is isolatedfrom the electrical current in the devices and no electrical current isconducted from the applicator or the patient.

Generally, the devices provided herein comprise a means for generatingand applying a high frequency alternating magnetic field, a means forcontrolling the alteration of the tissue or biomolecule containedtherein, a means for monitoring feedback related to heat generation, anda means for housing the device. Particularly, the devices may be handheld such that a hand held piece incorporates a source of radiofrequencyelectrical energy coupled to a coil and an impedance matching network toproduce an alternating magnetic field. When tissue is brought intoproximity of the alternating magnetic field, heating of the tissueresults as a consequence of either or both of dipole formation andoscillation or eddy current formation.

Optionally, cooling is provided to remove or disperse heat from thecoil, the source of RF electrical energy, or the surface of the skinalone or in combination. For example, a disposable or permanent tip, orcover placed between the induction coil and the skin provides athermally conductive surface that absorbs and distributes heat arisingfrom the skin surface, for example, as a heat sink. Alternatively, athermally conductive substance may be placed on the skin or tissue.Also, feedback monitoring of heat generation, eddy current formation inthe tissue, ultrasound detection of tissue alterations, changes inimpedence in tissues that lead to an impedance mismatch between themagnetic field applicator and the radiofrequency generator, hydration,etc. provides for the adjustable control of inductively generated heatin the tissue and/or device

The methods and devices provided herein exhibit the significant benefitsof, among other things, being non-invasive, not requiring electricalcontact with the body of the subject, and providing controllable heatingonly to a thin layer of tissue. The invention is useful not only forcosmetic procedures such as facial rejuvenation, wrinkle treatment, acnetreatment, hair removal, vascular lesion treatment, varicose veintreatment, curing of fillers, and treatment of cellulite, but also forsurgical procedures such as coagulation, cauterization or for inductionof biomolecular events, such as, but not limited to, a wound response,production of heat-shock proteins or an inflammatory response in tissue.

As described below, the invention provides a number of therapeuticadvantages and uses, but such advantages and uses are not limited bysuch description. Embodiments of the present invention are betterillustrated with reference to the Figures, however, such reference isnot meant to limit the present invention in any fashion. The embodimentsand variations described in detail herein are to be interpreted by theappended claims and equivalents thereof.

Radiofrequency Power Supply

The invention consists of a source of radiofrequency (RF) electricalenergy, which may be supplied using a RF generator such as sold byComdel, Inc. (e.g. CV1000 or CV500, preferably 40.68 MHz or 27.1 MHz;Gloucester, Mass.). The electrical output of the generator is coupled toan applicator consisting of an inductor in the form of a coil (for thegeneration of a magnetic field), which is further part of an impedancematching network that may additionally comprise a capacitor. The sourceof energy used may be a constant current or a constant voltage powersupply or may be a modulated current or a modulated voltage powersupply.

The power-supply is able to produce radiofrequency energy with a powerin the range 10-10,000 W and, depending on the application, preferablyin the range of about 100 to about 1000 W. The power-supply maytypically operate at frequencies of about 100 kHz to about 5.8 GHz.Preferably the frequency range is about 1 MHz kHz to about 5.8 GHz and,more preferably, the frequency range is at or near, or between 13.56MHz, 27.12 MHz, 40.68, 67.8 MHz, 95 MHz, 433.92, 915 MHz, 2.4 GHz.Beneficially, the RF generator may be frequency-agile; that is, as theimpedance of the load changes somewhat, the frequency output of the RFgenerator changes slightly to provide a better impedance match betweenthe load and the generator and so to maintain the output power within acontrollable tolerance.

Applicator

FIG. 1 is a sectional view of an applicator used to produce a magneticfield. A center copper tube 2220, which serves to conduct the RFelectricity but also serves as an input for refrigerant, is surroundedby a teflon cylinder 2240. Endcaps 2230 and 2270 server to position andhold the copper tube within the teflon cylinder. The center copper tube2220 is formed at the distal end of the applicator into a coil, 2280,which then is fixed parallel 2320 with the center copper tube anddirected to an exit 2210 out of the applicator; the coolant is directedout through exit 2210.

In order to provide impedance matching between the RF generator andapplicator, a ceramic insulator 2310 is positioned around the tefloncylinder 2240. The ceramic insulator has two capacitor rings, 2330 and2260, made up of copper pipe. The pipe 2320 is in electrical contactwith the capacitor rings. By adjusting the spacing 2250 between the twocapacitor rings, the impedance match between the RF generator andapplicator can be effected. The applicator is encased in a coppercylinder 2450 attached to the ground shield of the coaxial wire in orderto shield any stray radiated RF.

Handpiece

FIGS. 2A-2B show front and side views of one design for a hand piece3300, which is made of an electrically non-conductive material such asplastic, which surrounds or encases the applicator. A first main housing3500 is attached to a shield, or tip 3350, which is optionallydisposable, which may be thermally conductive, which serves to maintaincleanliness of the part of the handpiece which comes into contact withthe skin 4300, and which may serve to disperse or distribute heat.Optionally, the hand piece incorporates a coolant, for example, R-134a,contained in a second coolant housing 3520 and directed through asolenoid and pipe 3560 to an exit nozzle 3600. This coolant can becontrollably directed to the treated tissue before, during and/or afterthe treatment in order to limit the heating of the very superficialskin.

Cooling Endplate

FIG. 3 shows a view of an endplate 3550, on the distal end of the handpiece housing 3500. The endplate is in intimate thermal contact with thecoil 2280, which has circulating refrigerant or coolant within, and sothe endplate is cooled. This coolant may optionally be supplied from acirculating chiller utilizing water and antifreeze. Alternatively, gassuch as air, nitrogen, freon, R-12, R-134a, and carbon dioxide couldserve the purpose of cooling. An optional, removable shield or tip 3350may be in intimate contact with the endplate, thereby providing a meansfor the coolant to maintain an ambient temperature in the shield or tip.

FIG. 3 also shows an optional Faraday shield 3450, which is a conductiveelement intended to reduce capacitive coupling of coil to the subjectand so to minimize any stray electric field. Note that the coolingendplate may be in intimate contact with the coil in order to provideoptimal thermal conduction. This may be accomplished by molding or byforming the plate around the coil.

Pneumatic Applicator

FIG. 4 shows a partial view of an applicator incorporating a two-turnsolenoid coil 4150, the bore of which surround tissue 4260 whichextrudes from the skin 4300 up into the bore as a result of negativepneumatic pressure within the housing 3500. As the magnetic field withinthe turns of a solenoid is very much stronger than the field outside ofa pancake coil, and the geometry of the tissue within the bore isdifferent than illustrated in FIG. 2A, the power required to obtain aneffect is reduced and the effect on tissue can be more beneficial.Alternatively, a mechanical tissue-shaper may be positioned in contactwith the skin.

Combined Devices

In some aspects of this embodiment, the treatment may be inductively, orconductively or radiatively applied in combination with the use of analternating magnetic field. Additionally, the energy may be pulsed inorder to improve the thermal kinetics of the tissue heating. Examples ofapplied energy are radiofrequency energy, radiant energy or vibrationalenergy. The radiofrequency energy may have a frequency from about 20 kHzto about 40 GHz, and may be applied using coils, electrodes or one ormore anntennae. The radiant energy may have a wavelength from about 600nm to 11 μm. The vibrational energy may be sonic or ultrasonic with afrequency from about 20 Hz to 80 MHz. In the case of inductive heating,the energy may not be incident on the target, but may be induced in thetarget to be converted from one form to another.

In certain aspects, combined devices, using induction plus an energysource, e.g. laser or ultrasound, may enhance the effects or be used tocombine certain treatments. Because the interaction of laser energy andultrasound waves with tissue is physically different than the presentinvention, synergistic and combination effects are possible. Forexample, it may be desirable to treat the stratum corneum and epidermiswith an alternate form of energy simultaneously, or sequentially, whiletreating with magnetic induction, thereby resulting in greatervolumetric treatment of the skin. An applicator of radiant energy maycomprise an optical assembly which focuses the radiant energy on therelevant target or below the target surface to get a sub-surface effectsparing the superior surface. A pressure-wave applicator may consist ofa focused ultrasound transducer, which is coupled to the target tissuewith an acoustic impedance matching material, such as gelatin, mineraloil or glycerin.

Feedback Monitoring and Safety Interlocks

In its preferred embodiment (FIGS. 1, 2A-2B), the device includes ameans of monitoring the progress of the effect in tissue. For example,the alternating magnetic field results in tissue heating, this in turnalters the electrical properties of the target tissue. The tissueheating may have effects that alter electrical properties of the tissueeither transiently or permanently. The effects could includedehydration, coagulation and rearrangement of molecules for example.These changes may be detected as a change in impedance, or by monitoringhydration or eddy current formation. For example, as the impedance ofthe skin changes, the impedance match between the RF generator and thetissue/applicator is generally altered, and this change may be detectedthrough changes in power absorption, or changes in frequency. Thischange can alternatively be used as a signal to determine the level orduration of application of energy. Alternatively, the change in tissuecan be detected using ultrasound to detect morphological changes. Changein the flow of eddy currents may be detected as being an indicator ofthe progress of reaction, and may reflect morphological changes,dehydration or heat in the system.

As the tissue treatment process is initiated, the applicator (FIG. 1)and, most notably, the coil 2280, endplate (FIG. 3, 3550), and tissuemay increase in temperature. When the RF energy ceases, the temperaturewill fall. Such temperature changes can be monitored by devices such asthermocouples or thermistors. At times such devices can behaveerratically in the presence of strong electromagnetic fields. Therefore,devices such as infrared thermometers may be more suitable to monitorthe temperatures. These may be placed distal to the source of radiation,if required, and the signals transmitted through fiber optics.

Another approach to monitoring heat at the site of treatment involvesmonitoring temperature sensitive chemicals placed at the treatment site.These heat sensitive chemicals may be in the form of liquid crystalsdisposed on a film and placed in contact with the treatment site. Theliquid crystals may change color upon reaching certain temperaturethresholds, and may be monitored by collecting and detecting reflectedlight.

Transducers monitoring the temperature and power output of the RFgenerator, the reflected power into the generator, the presence of waterflow into the applicator and, if it is required, the generator, wherethe presence of a short-circuit anywhere, which are indicated by a rapidrise in current in the generator and/or applicator, are an importantsafety feature in the present invention. Other optional safetyinterlocks include mechanical or electrical transducers between thedisposable shield (FIG. 3, 3350) and the housing of the hand piece; if ashield is not present, the RF generator would not engage. Encoding ofthe interlock in the shield would ensure that a particular shield isonly used on a particular patient. Thermal switches are incorporatedwithin the device to shut it down if overheating occurs. Fast breakersquickly cut off the output if a power-output transient occurs. Multipleinterlocks are incorporated within the device, which prevents runningthe device with the cover removed. A foot pedal optionally isincorporated in order to minimize the possibility of unintentionalactivation of the device.

The induced magnetic field also may be actuated or amplified upondetection of a load. A relatively small current may be applied to thedevice while the device is not in proximity to a tissue target. As thedevice becomes proximal to the target, the change in impedance isdetectable, and this may be used as a signal to increase power to thedevice. In this example, the hand piece in place on the skin is matchedas a unit, i.e. skin and hand piece, to achieve the impedance match withthe power supply. Where there is a mismatch, the power will not bedelivered. This safety feature minimizes the exposure of the hand piececomponents to significant power load when the device is not applied totissue, thus potentially reducing wear of the device, as well asprotecting the patient and operator.

Methods of Treatment

The device may be used to induce changes in tissue by applyingalternating magnetic fields to the tissue such that currents are inducedwithin the tissue (eddy currents). These currents encounter resistanceand the result is the generation of heat. These eddy currents form mostefficiently where there is a moist, polar environment, thus enablingelectron displacement or ion flow within the target. Thus, for example,in skin, the generation of eddy currents in the moist underlying dermisis favored over the superficial dehydrated epidermis and stratum corneumlayers, and the underlying, more non-polar adipose layer. Thisdifferential in conductivity results in preferable heating of conductive(dermis) tissues over non- or weakly-conductive tissues.

Sufficient induced energy is required to generate enough heat toovercome the effects of cooling from the body and blood flow. Therefore,the coil is preferentially configured so as to place the magnetic fieldin close proximity to the skin surface and deliver a high frequency,intense alternating magnetic field such that heating in the dermis israpid and specific. Geometric considerations include size and shape ofthe coil so as to minimize distance between the coil and the skintarget. Rapid and specific heating of the dermis, as is achieved usingan intense alternating magnetic field, minimizes the total heat volumethat collateral tissues are subject to.

Variations in cooling of the skin surface may be achieved by increasingthe volume of coolant to the device, or surface of the skin. Thesevariations may be optimized to provide additional protection of thetissue proximal to the device from the effects of heating.

Disposition of a heat sink between the coil and tissue may providedispersion and distribution of excess heat. As the treatment progresses,heat may build up inside the tissue and at the interface of the device,thereby heating the device tip. The presence of a thermally conductivemass between the surface of the tissue and the device tip serves tominimize heating of the device, and may additionally serve to maintainan ambient temperature at the tissue surface.

In certain instances, coil geometry may result in uneven heating at thetip of the device. For example, eddy currents may form in the skin thatreflect the shape of the coil, particularly where the coil is a toroid,a ring-shaped heating pattern may result in the tissue. The removal ofheat in this instance serves to minimize the build-up of excess heat,i.e. the heat is distributed more evenly at the skin surface.

A scaffold or lattice structure may be placed within tissues to providesupport. The structure may be fixed or fused in place using methodsdescribed herein. For example, localizing a scaffold made of polylacticacid, or a similar polymer in proximity to fat layers found in or underskin could prove beneficial in the treatment of cellulite fat. Celluliteproduces an unattractive profile on the surface of skin due to the fatbeing squeezed between tissue structures resulting in upwelling of“fingers” of fat, which then distend the skin surface. Cellulite's causeis unclear, although it may result from fatty distension of thesuperficial fascia, which connects the dermis to the deep fascia.Attachment points to the dermis may be patent while surrounding areaslose structure and bulge, producing the “cobblestone” appearance on thesurface of the skin. By increasing the number of attachment points, orby fixing a mesh-like substrate in place to minimize bulge, or byheating the fat to achieve melting and flowing into the scaffold,cosmesis may conceivably be improved. The devices and methods describedherein may be used to heat and melt fat layers.

Another embodiment of the present invention allows for treatment ofacne, hair removal or treatment of varicose veins. It has beendetermined that the production of a critical amount of heat in tissuecan lead to a cascade of events that results in a therapeutic effect.Acne can be treated by causing thermal damage in the affected skin, andhair removal can result from thermal damage to the hair follicles. Theexact biologic mechanism behind these treatments is unclear, but tissuetightening may play a role. Alternatively, sub-lethal damage to the hairfollicles can actually result in stimulating hair growth. Sub-lethaldamage leads to a cascade of wound-response events such as theproduction of cytokines, interleukins and heat-shock proteins. Theseendogenous events can be beneficial and probably underlie the salientevents in, for example, stimulating hair-growth. The instant inventioncan induce all of these events.

Treatment of skin wrinkles sometimes can employ botulism toxin,whereupon an injection of toxin in or around the nerves associated withthe wrinkle temporarily relax the muscle leading to reduction in theappearance of the wrinkle. Recently, electrosurgical ablation of thenerve has been shown to result in a good cosmetic effect and may benefitfrom being permanent. The problem with electrosurgical ablation of thenerves is the same as the problems associated with electrosurgicalgenerators in other procedures, i.e. there is a risk of burning andexcess heating. The present invention provides a means with which toablate the nerve in a non-contact mode, whereby a metal tip catheter maybe placed into the nerve, or near the nerve, and the tip exposed to amagnetic field generated from a coil in the near vicinity.

Coagulation is a very important technique in surgery as it provides ameans to kill tissue without dissection, thus eliminating potentiallytoxic smoke and char, and by not removing tissue, allowing formechanical integrity to be maintained for a period of time. Standardelectrosurgical and electrocautery devices usually produce smoke whenused to coagulate tissue (smoke is a potential source of carcinogens orviruses), and dry tissue tends to stick to the electrosurgical electrodewhich then results in re-bleeding when the electrode is removed from thetreatment site. A non-contact way of coagulating tissue, using theinstant invention, would be or paramount importance in surgery. Theinstant invention exhibits the benefit and when the tissue is heated anddessicates, coupling between the magnetic field and tissue decreasesthus limiting the heating and eliminating the possibility of smoke orcharring.

The following examples are given for the purpose of illustrating variousembodiments of the invention and are not meant to limit the presentinvention in any fashion.

EXAMPLE 1

Applicator

The pancake coil is made from 3.5 turns of 0.125″ OD copperrefrigeration tubing and has a diameter of 1.4″. The coil must be hollowtubing to allow water or other cooling fluid to flow through it anddissipate the ˜500 W of heat generated. The main capacitor (FIG. 1,2260) has a value of ˜70 pF which resonates with the coil at 40.68 MHz(FIG. 5). Earlier prototypes were made with a Teflon dielectric(Kr=2.2), but the size of the capacitor became too unwieldy to use in ahandheld device. Capacitance can be calculated using the formula for acylindrical capacitor: C=(2 π*Kr*μo)/(In(b/a)), where, C=capacitance inpF per unit length, Kr=dielectric constant (9.8), μo=permittivity offree space=8.85 pF/m, b=outer diameter, a=inner diameter

The length of the capacitor is inversely proportional to the Kr of thedielectric used, so alumina was chosen for its high Kr and its otherdesirable properties: Good thermal conductivity—30 W/m*K; Highdielectric strength—200 ACV/mil; High dielectric constant—9.8; Availablein tube form at low cost; Dimensions compatible with available copperpipe sizes. The particular alumina tube used is 3.5″ long, 0.625″ OD,0.500″ ID, 99.8% alumina (CoorsTek part #65677). The inner and outer“plates” of the cylindrical capacitor are copper pipes that fit closelyto the inner and outer diameters of the alumina tube.

It is critical that the copper tubes fit the alumina as closely aspossible, as any air gaps will act as low value series capacitors andoffset the advantage of the high Kr material. Since it is impossible tocompletely eliminate the air gaps, the entire capacitor assembly ispotted in silicone with a Kr of 2.7 to regain some of the capacitancelost by the gaps, and also to help prevent the high voltage RF arcswhich are bound to occur at these high voltages. The silicone, throughvacuum encapsulation, completely surrounds all high voltage points onthe device. The tuning capacitor (FIG. 1, 2330), is formed in the sameway as the main capacitor, although much smaller in value and size.

Shielding was found to be an important part of the design to reducecircuit detuning caused by the operator's hand, as well as reduce strayradiation from the connecting coax and RF generator. The shield enclosesall the internal workings of the device, and is made from 1″ copper pipeand an end cap. The shield also serves as a liquid tight container tohold the silicone (Momentive RTV615) during the vacuum encapsulationprocess.

Water-cooling is used to effectively cool both the coil and the coaxialcapacitor assembly. Water flows in series through the center capacitorpipe, then the coil, and back through the copper tubing soldered to theouter capacitor pipe. At a power level of 500 W and 0.75 liters/minflow, the water temperature rise is about 9° C.

A resonant circuit was the topology chosen to maximize the current inthe coil because this type of circuit has the property that thecirculating current is approximately Q times the applied current, andthe Q of this circuit is about 60. The primary goals of the circuit areto maximize the current in the coil as well as provide a good impedancematch to the 50 ohm RF generator driving it.

The alumina tube is cut to length using a wet cutting diamond saw. Theinner pipe is then prepared by turning it down on a lathe to a size thatjust slides into the ceramic without forcing it. Copper disks and shortlengths of 0.125″ copper tubing are soldered into the ends of the pipe,one going to the flexible silicone water tubing, and the other to thepancake coil.

A small batch of RTV615 is mixed up and de-aired in a vacuum chamberusing a Welch 1400 vacuum pump. The mixture is considered de-aired afterit foams up and then recedes (˜30 minutes). About 1 ml of the RTV ispoured into one end of the vertically held inner pipe/ceramic assemblyand cured at 100° C. for one hour, forming a silicone “plug” in that endto prevent the liquid RTV from running out during the next step. Aftercooling, the assembly is inverted and more RTV is poured into the otherend and allowed to sink in and fill the gaps between the inner pipe andceramic under vacuum. After sufficient time in the vacuum (no morerising air bubbles visible), the assembly is removed from the vacuum andagain cured at 100° C. for one hour.

Adhesive backed copper foil tape is tightly wrapped on the outerdiameter of the ceramic assembly over a distance slightly shorter thanthe outer capacitor pipe. The purpose of the tape is to get a tightfitting conductor around the ceramic with minimal air gaps. The tape ismechanically weak and not thick enough to adequately conduct the heatgenerated, so copper pipe couplers are then bored out to slide over thelayer of copper tape, and will be soldered in place once the initialtuning is completed. The “ring” pipe is bored out to tightly fit theceramic at this time as well. About 0.4″ of free ceramic is left on theend for high voltage insulation and spacing.

Next, the pancake coil is wound from the 0.125″ refrigeration tubing,and the short end of the tubing from the center is coupled and solderedto the tubing stub on the capacitor assembly. The other (long/grounded)end of the tubing is positioned parallel and against the outer pipe(ground), and is temporarily held in place with copper tape for tuning.

A length of test coax from a network analyzer is temporarily solderedbetween ground and the ring. The outer pipe and ring are slid back andforth to obtain an impedance match at a frequency higher than the finaloperating frequency, knowing that the frequency will drop afterencapsulation with silicone. Once the correct position is found, thegrounded tubing of the pancake coil is soldered along the outer pipe andthe gap between the copper foil and outer pipe is flooded with solder.

The silicone water tubing is now attached to the other stub of 0.125″tube on the inner pipe with a bus wire “hose clamp” and the connectioncovered with heatshrink. The Teflon sleeve is then slipped over thisconnection for high voltage insulation.

At this point the 1″ copper shield pipe is positioned over the innerworkings, with the grounded end of the coil's copper tubing exiting theshield through a slot in the side. The flexible silicone water hose andcoax cable are fed through holes in the pipe cap; the coax braid issoldered to the inner wall of the shield, and the coax center conductorto the ring on the ceramic assembly. After pressing the pipe cap inplace, and centering the ceramic assembly in the shield, the groundtubing is soldered to the shield and the slot filled with solder for aliquid tight seal. A final tuning check is made with a network analyzerwith the shield in position, and any necessary pre-encapsulationadjustments are made.

Next, another (˜80 g) batch of RTV is prepared and de-aired in thevacuum chamber as before. With the device held vertically and open atthe top, the assembly is slowly filled with RN and then vacuum pumpedfor about an hour to remove all air bubbles. The vacuum process iscomplete when air bubbles stop rising to the surface. The device is thenremoved from the vacuum and cured for 4 hours at 65° C. The longer,lower temperature curing cycle is used because it is below the coaxcable's maximum temperature rating. After curing and cooling, the secondsilicone water hose is attached to the copper ground tubing with a buswire “hose clamp” and the connection covered with heat shrink.

EXAMPLE 2

Tissue Tightening In Vitro

Ovine and human tissue samples were cut into 2 cm×2 cm sections andinductively treated using 400 W power generated from a an ENI 6B powersupply operating at 13.6 MHz. The coil was 2 cm in diameter and placed 2mm from the tissue. Exposure was for 20-30 seconds. Samples of lung,artery, and skin demonstrated macroscopic shrinkage of approximately5-20% depending on length of exposure. Skin and lung samples were placedin formalin and evaluated by thin section histology. Examination ofMason-trichome stained sections demonstrated that collagen fibrils werepacked more closely together in the treated versus untreated sections.

FIG. 6 shows measurements taken at 27 MHz and 600 W. Bovine muscle,bovine fat, ovine skin, and human blood were used for comparison. Thetissues were cut to 2×2˜5 cm samples. Each sample was placed directly onthe cap of the 27 MHz device and imaged from above with a Raytek IRthermometer. The device was activated and the time to heat was recorded,(n=3 for each tissue type).

FIG. 7 shows porcine fat, muscle and skin were used for comparison. Thetissue samples were measured for thickness to ensure consistency betweensamples. The samples were between 1.5-2.0 mm in thickness. The sampleswere placed on the faceplate which is 4 mm thick PVC and imaged fromabove with a Raytek IR thermometer. The device was turned on and thetime for the sample to reach 70° C. was recorded. The IR thermometer islimited to recording the tissue surface opposite that which is incontact with the device. Therefore, it is believe that the actualtemperature of the tissue was greater than indicated on the graph.

EXAMPLE 3

Tissue Tightening and Dermal Thickening In Vivo

Rat skin was treated with the coil device at 40 MHz and 350 W powerdelivery. The device was held juxtaposed to the skin of anesthetizedrats until visible shrinkage was evident without cooling (treatment timett=24 seconds), with cooling (that is, with the refrigerant circulatingthrough the coil and endplate, tt=29 seconds) and at tt=27 seconds. Agrid was drawn on the back of the animal prior to treatment and wasphotographed before and after treatment and on post op day one. Theimage was digitized and the grids were compared down to the pixel foracute shrinkage. The treatment site was biopsied on post op day two foracute wound response and on post-treatment day 21 to ascertain collagendeposition. Temperature of the epidermis was also measured followingtreatment. After treatment, the temperature of the surface of the skinwas at or around 42° C.

By measuring the distance between the gridlines on the skin, it waspossible to determine that acute shrinkage of 5% with cooling and 8.5%without cooling occured. After 1 day, the skin exhibited a sustainedshrinkage of 2.5% with cooling and an increase to 15.9% without cooling.Consistent results were obtained with guinea pig skin, which is known tobetter mimic human dermal tissue. Treated guinea pig skin shrunk 10.9%with cooling and 11.6% without cooling immediately following treatment.

EXAMPLE 4

Tissue Tightening and Dermal Thickening Using 27.2 MHz

The dorsa of four Sprague-Dawley rats were shaved, then the skin wasinductively treated using 600 W power generated from a 27.2 MHz powersupply. The two-turn pancake coil was 1.5 cm in diameter, and placedagainst the tissue using a 2 mm spacer composed of Teflon. Exposure wasfrom 5 to 10 seconds and cooling of the coil was used. Contraction ofthe tissue was noted after several seconds of treatment. Biopsies weretaken at 21 or 28 days, and histologically stained using eosin or MasonTrichome.

Biopised samples at each timepoint showed a thickening of the dermis ascompared to untreated controls (FIGS. 8A-8C), as well as production ofneo-collagen (FIGS. 9A-9B). FIG. 10 shows a model of the expected modeof action produced by this inductive heating using alternating magneticfield energy on the collagen within the treated tissues; the collagendenatures and coagulates, sometimes involving cross-linking between theproteins, resulting in a shrinkage in the volume of the tissue.

EXAMPLE 5

Skin Tightening in Human Subjects

A 27.1 MHz radiofrequency generator (Comdel CV 500) was fitted with ahand piece comprised of a 3 cm diameter, multi-turn coil and matchingnetwork. Four human subjects received treatments of from 8 to 11 secondson the abdomen at 250 W power output from the Comdel. Skin tighteningwas apparent after 72 days as evidenced by a reduction in visiblewrinkles, skin smoothing and reduction of waist size. The visualappearance of the skin (skin rejuvenation) was also improved.

The following references are cited herein.

-   1. U.S. Pat. No. 7,189,230.-   2. Leitgeb, N. Bioelectomagnetics 2010, 31:12-19.-   3. Franco, W. et al, Lasers Surg. Med. 2010; 42:361-370.-   4. U.S. Pat. No. 7,463,251-   5. Anderson, R R, Arch Dermatol, 2003, 139:787-788.-   6. Gilchrest et al., Plast. Reconstr. Surg. 1982; 69:278-83.-   7. Klein, M. 2008 Deep Heat, www.emedicine.medscape.com.-   8. Cameron, M. In: Physical Agents in Rehabilitation, Saunders.

Any patents or publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. These patents and publications are hereinincorporated by reference to the same extent as if each individualpublication was specifically and individually incorporated by reference.One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objects and obtain the endsand advantages mentioned, as well as those inherent therein. It will beapparent to those skilled in the art that various modifications andvariations can be made in practicing the present invention withoutdeparting from the spirit or scope of the invention. Changes therein andother uses will occur to those skilled in the art which are encompassedwithin the spirit of the invention as defined by the scope of theclaims.

What is claimed is:
 1. A method of treating skin by inducing heat indermis of the skin to cause a biological response in the dermis, themethod comprising: contacting the skin of the individual with a shieldat a distal end of an applicator; transmitting radiofrequency energy inthe form of an alternating current through a straight proximal portionof a copper tube in the applicator to generate a high frequencyalternating magnetic field with a coil in a distal portion of the coppertube, wherein the coil is housed within the shield of the applicator;applying the high frequency alternating magnetic field to the dermis toproduce preferential heat production in the dermis through inductivecoupling with the dermis, wherein the heat production causes thebiological response in the dermis; cooling the skin with a coolantapplied by the applicator; removing the shield from the applicator aftertreating the skin; and disposing of the shield.
 2. The method of claim1, further comprising applying an additional form of energy to thedermis concurrently or sequentially with the alternating magnetic field,wherein the additional form of energy is selected from the groupconsisting of radiant energy, acoustic energy and vibrational energy. 3.The method of claim 1, further comprising: monitoring feedback from saidalternating magnetic field; and adjusting said heat production in saidmoist conductive tissues of the dermis based on the feedback.
 4. Themethod of claim 3, wherein monitoring feedback comprises performing atleast one detecting step selected from the group consisting of detectingheat from the heat production in the dermis, detecting eddy currentsformed in the dermis, detecting hydration changes in the dermis, anddetecting impedance changes in the dermis.
 5. The method of claim 4,wherein the detecting heat from the heat production in the dermiscomprises at least one of monitoring heat sensitive liquid crystal mediaor monitoring infrared radiation.
 6. The method of claim 4, whereinmonitoring feedback further comprises monitoring heat generated byanother source of energy selected from the group consisting of radiantenergy, plasma energy, acoustic energy, bipolar electrosurgical energyand monopolar electrosurgical energy.
 7. The method of claim 1, whereinthe cooling of the skin comprises circulating a coolant through thecopper tube to cool the shield of the applicator.
 8. The method of claim1, wherein the cooling of the skin comprises directly applying a coolantto the skin via a coolant nozzle on the applicator.
 9. The method ofclaim 1, wherein the shield of the applicator comprises a thermallyconductive surface that acts as a heat sink that passively dispersesheat.
 10. The method of claim 1, wherein the biological response isselected from the group consisting of tissue coagulation, cauterization,tissue contraction, tissue shrinkage, induction of wound response, andproduction of collagen.
 11. The method of claim 1, wherein thepreferential heat production in the moist conductive tissues of thedermis improves an appearance of the skin by at least one of reducingwrinkles in the skin or reducing laxity of the skin.